A method for manufacturing a molded product includes a powder metallurgy method for manufacturing a molded product by solidifying powders. The powder metallurgy method includes a die press molding method for manufacturing a molded product by performing sintering after the powders are filled into a mold and compressed and molded by a molding machine.
Furthermore, the powder metallurgy method includes a powder lamination molding method. As a method of the powder lamination molding method, a power bed fusion method and a binding agent spraying method are exemplified. The power bed fusion method is a method for manufacturing a molded product by repeatedly emitting laser or an electric beam toward the powders spread on a table and sintering or melting the powders. The binding agent spraying method is a method for manufacturing a molded product by repeatedly spraying a binding agent toward the powders spread on the table and combining the powders.
Here, in the die press molding method, a high filling rate of the powders filled into the mold is required. Furthermore, even in the powder lamination molding method as exemplified by the power bed fusion method and the binding agent spraying method, a high filling rate of the powders spread on the table is required. In order to improve the filling rate of the powders, it is essential to increase flowability of the powders.
Furthermore, as a method of the powder lamination molding method, a directional energy method is exemplified. The directional energy method is a method for manufacturing a molded product by spraying powders toward a place irradiated with laser or arc which is a heat source and melting and concreting the powders at the irradiation position. Even in the powder lamination molding method as exemplified by the directional energy method, the high flowability of the powder is essential in order to prevent clogging in a flow path through which the sprayed powders pass.
In Patent Literature 1, a secondary particle obtained by three-dimensionally combining primary particles with gaps is used for a powder used in the powder metallurgy method. In Patent Literature 1, by using the secondary particle obtained by combining the primary particles, a particle size of the secondary particle is made larger than the primary particle, and flowability of the power is improved. Note that, as the powder used in the powder metallurgy method, a nonmetallic powder can be exemplified, in addition to a metallic powder. The nonmetallic powder used in the powder metallurgy method includes a ceramic powder.